A much more complicated idea of law emerged from the project of St. Thomas Aquinas to reconcile the revealed Christian truth with the pagan philosophy of Aristotle. This project required Aquinas to restore the link between law and a cosmic order while at the same time acknowledging, as Christian doctrine required, that men cannot read the mind of God.

Aquinas' solution rests on accepting, in a modified form, the Aristotelian view of nature that Augustine had rejected. In the Thomistic picture, the model for order in human society is the cosmic hierarchy, in which the higher moves the lower by means of superior natural powers divinely assigned to the higher. The universe is a hierarchy of “movers,” in which power descends from the first mover to subordinates in their due order, just as the plan of a work of art descends from the chief craftsman to the craftsmen who work under him. Just as in nature, where higher things move the lower because of the preeminent natural powers conferred upon them by God, so also in human affairs superiors impose their will upon inferiors because of the authority established by God. The submission not only of children to the father, but also of families to the political ruler is as natural as the rule of the soul over the body and of God over the world.